package two;

public class A025 {


    //环形链表
    public boolean hasCycle(ListNode head) {

        ListNode slow = head;
        ListNode fast = head;
        while(fast != null && fast.next!=null) {
            slow = slow.next;
            fast = fast.next.next;
            if(slow == fast) return true;
        }
        return false;
    }
}
